Information on angels is sort of on a "need-to-know basis." All one needs to know is that angels are messengers, protectors, and guides sent and created by God. If you meet one, it's serious business. You may meet one in the guise of a human, so be nice to everyone.

If you include fallen angels in your inquiry, it's important to know that they're 100% evil 100% of the time, and that they can be subtle. I suppose that this suggests that angels are 100% good 100% of the time, meaning that angels and demons have much more "focused" spirits than we.